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Biomedical subjects

E Noguchi

Publications and source records attributed to E Noguchi.

108 records · Page 6Linked to original sources
PubMed1977

Monoamine oxidase in developing chick retina.

The developmental changes in monoamine oxidase (MAO) activities towards 5-hydroxytryptamine (5-HT) and beta-phenylethylamine (PEA) in chick retina were investigated. The whole pattern of the developmental changes in MAO activity towards 5-HT was similar to that towards PEA, even though the activity towards 5-HT was much lower than that towards PEA during the period from the 12th day of incubation to the 14th day after hatching. The MAO activities on the 12th day of incubation were low and increased remarkably until the 18th day of incubation. Then they remained unchanged until the 7th day after hatching; therefore, they decreased. The activities measured on the 14th day after hatching are on the same level as those of an adult. The multiplicity of MAO in the retinae of a chick on the 12th day of incubation and of an adult was also studied with specific inhibitors. The result showed that the major part of MAO in chick retina is type B enzyme; that type A MAO in the retina of an adult is, however, relatively higher than that in the retina of the embryo on the 12th day of incubation. It was found that an appreciable amount of MAO activity towards 5-HT in chick retina is due to type B MAO.

Age Factors↗
PubMed1976

A simple fluorometric assay for type B monoamine oxidase activity in rat tissues.

A simple fluorometric assay for monoamine oxidase (MAO) [EC 1.4.3.4] activity towards beta-phenylethylamine (PEA) was devised. The procedure consists in measuring the disappearance of PEA fluorometrically. The disappearance of PEA was completely inhibited by pargyline, a potent inhibitor of MAO. MAO activity for PEA was linear with 10 mg to 100 mg of liver tissue in 3 ml of reaction mixture for up to 90 min of incubation. Using this method, the V max values and the apparent Km values of MAO for PEA in several rat tissues were determined, and compared with those for benzylamine and 5-hydroxytryptamine (5-HT).

Animals↗
PubMedDate not supplied

Enhancement of methoxamine-induced contractile responses of rat ventricular muscle in streptozotocin-induced diabetes is associated with alpha1A adrenoceptor upregulation.

AIM: To clarify the time-related changes in cardiac function and the mechanism underlying the cardiac dysfunction present in diabetes mellitus, we studied mechanical responses induced by alpha(1)- and beta-adrenoceptors, the Ca(2+)-entry promoter Bay K 8644- and ryanodine (an agent known to inhibit Ca(2+) release from the sarcoplasmic reticulum) in papillary muscles from streptozotocin (STZ)-induced diabetic and age-matched control rats. METHODS: Male Wistar rats received a single injection of STZ (60 mg kg(-1)) via the tail vein to induce diabetes. For the mechanical studies, papillary muscle preparations were suspended in an organ bath and isometric contractions were measured in 1-, 4-, and 10-week STZ-induced diabetic and age-matched control rats. RESULTS: In 1-week diabetic rats, the contractions induced by isoproterenol, methoxamine and Bay K 8644 were unchanged (vs. age-matched controls). In 4-week diabetic rats, (a) the isoproterenol- and Bay K 8644-induced contractions were impaired, (b) sensitivity to ryanodine was reduced, whereas (c) the methoxamine-induced contraction was unchanged. In 10-week diabetic rats, the isoproterenol- and Bay K 8644-induced contractile responses were impaired and the sensitivity to ryanodine was reduced, but in sharp contrast the methoxamine-induced contraction was enhanced. Both the mRNA level for the alpha(1A) adrenoceptor (but not the alpha(1B) or alpha(1D) mRNAs) and alpha(1A) adrenoceptor protein were increased in 10-week diabetic rats (vs. age-matched controls). CONCLUSION: These results suggest that impairments of beta-adrenergic and Ca(2+)-handling mechanisms occur early in the development of cardiomyopathy in STZ-induced diabetic rats, and that this is followed by augmentation of alpha(1A) adrenoceptor-mediated inotropy due to alpha(1A) adrenoceptor upregulation.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMedDate not supplied

No evidence for an association between a variant of the mast cell chymase gene and atopic dermatitis based on case-control and haplotype-relative-risk analyses.

Atopic dermatitis (AD) is a chronic relapsing dermatitis which belongs to the group of atopy-related diseases as well as asthma and allergic rhinitis. As a probable genetic risk which may contribute to the organ specificity of AD, an association between AD and a genetic variant of the gene encoding mast cell chymase (MCC), which has chymotrypsin-like specificity and is abundant in skin mast cells, has been reported in a Japanese population. We tried to confirm the role of this polymorphism in the development of AD in a Japanese population. A case-control analysis using 100 AD patients and 101 controls did not show a significant difference in the frequency of the BB genotype between the patient and control groups (odds ratio 1. 12, p = 0.81). The haplotype relative-risk analysis using 69 patient-parents trios did not suggest an association (chi2 = 0.177, p = 0.92). Thus, we failed to confirm the association between the polymorphism in the MCC gene and AD in the Japanese population.

Adult↗
PubMedDate not supplied

The effects of long term Tranilast administration on bronchial hypersensitivity in asthmatics.

Tranilast is an oral antiallergic agent developed in Japan. This study investigated the effect of prolonged administration of Tranilast on the bronchial sensitivity of 18 asthmatic subjects. They were treated for either less than 3 months or more than 3 months continuously. Methacholine loading testing was used to assess bronchial reactivity, and the respiratory parameters were recorded on an Astograph. Patients treated for longer than 3 months showed a significant decrease in bronchial sensitivity (p less than 0.05). The anticholinergic and bronchodilatory properties of Tranilast were also investigated in 8 subjects. No significant anticholinergic or bronchodilatory effects were observed following a single oral dose of 100 mg of Tranilast.

Adult↗